Thank you for adding this information.I am a great great granddaughter of Julius Kosack.I call him Julius because this is how I knew him growing up.I have spent some time looking at the Breslau Church records on microfilm here in the United States to document what my grandmother had told me.
My grandmother, Elsie Agnes Probst, was proud of her family and would tell us the stories she heard and remembered from her childhood.Her mother Olga Kosack Probst never returned to Breslau as she and her husband Theodore Probst had planned when they came to America. I do know there were letters from Breslau to Olga. Julius never wrote Olga or sent any communication.I know a siter named Hilda sent letters. The children all learned German as their primary language and Elsie started school knowing only German.
I recently found the Baptismal record for Julius and the last name was spelled Kosag not Kosack.Julius's father Carl was a potter.I also found the Baptismal of Julius's sister in 1833.
Thank you so much for sharing and I hope to hear from you.